With development of mobile communications, the demand for positioning services is rapidly increasing. The Global Positioning System (GPS) has been widely used outdoors with very high precision, improving user experience. Related studies have shown that 80% of data application is implemented indoors. However, in most cases, no GPS signal can arrive in an indoor environment, and an indoor positioning requirement cannot be met if GPS is still used for positioning.
Currently, a method for indoor positioning is to perform indoor positioning by using an indoor distributed NodeB system (iDBS). Based on iDBS positioning, there are mainly the following two methods:
First: Positioning is performed on a terminal side. A terminal performs positioning based on downlink signals received from multiple remote radio units (RRU). The RRUs send positioning reference signals (PRS) at specific intervals, and different RRUs send different PRSs, or different identifiers are allocated to different RRUs, so as to position the terminal. This can avoid confusion between the RRUs.
Second: Positioning is performed on a network side. A baseband unit (BBU) performs positioning based on uplink signals received by RRUs from a terminal. The BBU determines, according to whether an RRU first receives the signal from the terminal, whether the RRU is closest to the terminal, and uses the closest RRU to measure a round trip time RTT) used to reach the terminal. The BBU selects at least three RRUs, and may calculate a location of the terminal according to distances from the three RRUs to the to-be-positioned terminal.
However, both of the foregoing two methods in the prior art have disadvantages. In the positioning method on the terminal side, power consumption of the terminal is increased because calculation is performed on the terminal side. In addition, when there are a relatively large quantity of RRUs, sending PRSs at intervals leads to a relatively long positioning measurement period, affecting normal data communication efficiency. Because different RRUs are distinguished by using different identifiers, an existing cellular communication protocol needs to be correspondingly modified, resulting in poor compatibility of the solution.
In the positioning method on the network side, the BBU can obtain time information only after a communication round trip, invisibly increasing network load. In a dense scenario, a large quantity of positioning signals are exchanged, interrupting a normal data service.